In general, a washing machine is an apparatus which washes laundry using electric power, and includes a tub which stores wash water, a rotating tub which is rotatably installed in the tub, and a motor which drives the rotating tub to be rotated. A series of washing processes such as washing, rinsing, and spin-drying are performed using a rotating motion of the rotating tub.
When the rotating tub is rotated, if the laundry is not uniformly distributed in the rotating tub and is crowded to a certain portion, vibration and noise are generated by a rotation of the rotating tub. In a severe case, components such as the rotating tub and the motor may be damaged. Therefore, the washing machine has a balancer which damps load unbalance generated in the rotating tub and stabilizes the rotation of the rotating tub.
However, in the prior art, a movement of the balancer is passively performed, and the balancer may not be precisely located at a position which damps an unbalanced load of the rotating tub, and thus the vibration and the noise may not be minimized. To solve this problem, an active balancer which receives power from an outside to be driven actively has been studied.